The US Army is receiving the first of its new Mk46 Special Purpose Weapons. Developed from the M249 Squad Automatic Weapon, the Mk46 has several distinctive features. Both are 5.56mm belt-fed weapons. The Mk 46 barrel is fluted (has grooves cut in the length of it) to withstand heat better. The gas system is a monobloc design without small parts that could be lost. The weapon is 908mm long. The bolt is finished with electroless nickel, allowing it to fire 1,000 rounds without any lubrication. There are four Picatinny Rails on the weapon, one on top, one on each side, and one under the barrel. These can be used by the gunner to customize the weapon with sights, handgrips, laser aiming devices, and flashlight systems. The Army plans to buy 2,506 of these M46 weapons, mostly for use by special forces units.--Stephen V Cole